Deposition Of Dots Research Articles

Deposition of CdSe Nanocrystals in Highly Porous SiO2 Matrices-In Situ Growth vs. Infiltration Methods.

Embedding quantum dots into porous matrices is a very beneficial approach for generating hybrid nanostructures with unique properties. In this contribution we explore strategies to dope nanoporous SiO2 thin films made by atomic layer deposition and selective wet chemical etching with precise control over pore size with CdSe quantum dots. Two distinct strategies were employed for quantum dot deposition: in situ growth of CdSe nanocrystals within the porous matrix via successive ionic layer adsorption reaction, and infiltration of pre-synthesized quantum dots. To address the impact of pore size, layers with 10 nm and 30 nm maximum pore diameter were used as the matrix. Our results show that though small pores are potentially accessible for the in situ approach, this strategy lacks controllability over the nanocrystal quality and size distribution. To dope layers with high-quality quantum dots with well-defined size distribution and optical properties, infiltration of preformed quantum dots is much more promising. It was observed that due to higher pore volume, 30 nm porous silica shows higher loading after treatment than the 10 nm porous silica matrix. This can be related to a better accessibility of the pores with higher pore size. The amount of infiltrated quantum dots can be influenced via drop-casting of additional solvents on a pre-drop-casted porous matrix as well as via varying the soaking time of a porous matrix in a quantum dot solution. Luminescent quantum dots deposited via this strategy keep their luminescent properties, and the resulting thin films with immobilized quantum dots are suited for integration into optoelectronic devices.

Uniformly deposition of iron phosphide quantum dots on the microscopic spongy B-C3N4 and its efficient degradation of ciprofloxacin by photo-self-Fenton process

In this research, iron phosphide quantum dots (FeP QDs) are synthesized and anchored on the microporous spongy BxCN uniformly through a novel hydrothermal-phosphorization processes. FeP@BxCN shows excellent photo-self-Fenton capability and applies to eliminate CIP from aqueous solution. Results indicate both photocatalysis and self-Fenton processes contribute to CIP degradation (photocatalysis: 69.1 %; self-Fenton: 28.2 %). The decoration of FeP QDs could effectively suppress the recombination of photogenerated carriers and improve the photocatalysis performance. They also accelerate the transformation of in situ H2O2 to •OH radicals thus enhance the efficiency of self-Fenton process. Furthermore, FeP QDs shows pretty low consumption during the self-Fenton process because of the regeneration mechanism between cationic iron species, H2O2 and anionic phosphorus. The existence of intermediate valence iron (Feɛ+) and anionic phosphorus (Pɛ-) ensured the regeneration of Fe(II) and the circulation between Fe(II), Feɛ+ and Fe(III). Optimal CIP degradation efficiency could be achieved under neutral condition and the corresponding CIP removal efficiency are 97.3 % when the initial concentration is 30 mg•L−1 and reaction within 120 min. Results propose a meaningful exploration for antibiotics degradation via photocatalytic-self-Fenton technology.

Enhanced detection of glucose with carbon quantum dot-modified copper oxide: Computational insight and machine learning modeling of electrochemical sensing

Poor conductivity and surface passivation pose critical challenges in metal oxide structures during their application for non-enzymatic oxidation. To address this, we systematically employed in-situ deposition of carbon-quantum dots (C-dots) over copper oxide (CuO), enhancing its electrocatalytic properties for direct non-enzymatic glucose oxidation in alkaline media. The process involved the systematic deposition of varying wt.% of C-dots onto the CuO nanostructure. The electrode’s sensing capability was assessed through CV, DPV, and amperometric measurements, evaluating its suitability in high (0.1 to 0.85 mM) and low glucose concentration levels (15 to 225 nM) with a representative LOD of 1.4 nM (17142.86 µA mM−1 cm−2). Additionally, the CuO-Cdot-16.6 protective coating allowed for long-term working capability, with chronoamperometric measurement confirming a 99 % current retention ability compared to pristine CuO’s 39 % retention during 3500 s of continuous measurement. DFT calculations further confirmed the efficacy of CuO substrate as a scaffold for glucose adsorption. The stable CuO-glucose complex formed due to energetically favorable conditions further strengthens its potential as a sensor. Successful recoveries of spiked glucose serum samples validated the sensor’s practical usage in complex matrices. Moreover, Machine learning was also adopted to validate the accuracy of glucose detection, where artificial neural network (ANN) model emerged as a suitable model to interpret the DPV derived data relationships, adding in sensor working capability and promising its future application in precision/intelligent healthcare.

One‐Step Synthesis and Deposition of Metal Oxides: NiO Quantum Dots as a Transport Layer for Perovskite Photovoltaics

One‐step synthesis and deposition of nickel oxide quantum dots using a gas‐phase microplasma process is demonstrated and their applicability as a transport layer for solar cell devices is shown. The process uses a solid nickel metal wire as sacrificial electrode, and the concentration of oxygen gas required in the synthesis is investigated. The quantum dots are characterized for physical, chemical, and optical properties and critical process parameters such as the process throughput are also estimated. Direct one‐step deposition directly on perovskite solar cells is carried out using a computer‐controlled x–y stage and the performance of the solar cell device is assessed.

0D/2D dual Fenton α-Fe2O3/Fe-doped g-C3N4 photocatalyst and the synergistic photo-Fenton catalytic mechanism insight

A novel dual Photo-Fenton photocatalyst Fe2O3–Fe–CN with excellent Fe(III)/Fe(II) conversion efficiency and trace metal ion leaching rate has been fabricated by in-situ deposition of α-Fe2O3 quantum dots on ultrathin porous Fe-doped carbon nitride (Fe–CN) nanosheets. The iron species in Fe–CN and α-Fe2O3 QDs constitute a mutually reinforcing dual Photo-Fenton effect. The 4% Fe2O3–Fe–CN showed superior performance with kobs values 8.60 and 4.80 folders greater than pure CN and Fe–CN, respectively. The synergistic effect between α-Fe2O3 QDs and the ultrathin porous structure of Fe–CN is the primary reason for the outstanding catalytic performance exhibited by α-Fe2O3/Fe–CN. On one hand, the ultrathin porous structure of Fe–CN promotes the rapid transfer of photogenerated electrons. On the other hand, the efficient photogenerated charge separation at the α-Fe2O3/Fe–CN interface enables more photogenerated electrons to participate in the Fe3+/Fe2+ conversion and H2O2 activation. The trapping experiments demonstrate that •OH and •O2− are the primary active species in TC degradation. This work presents novel insights into the design of efficient heterogeneous Fenton catalysts for practical applications.

Carbon dots on LAPONITE® hybrid nanocomposites: solid-state emission and inter-aggregate energy transfer.

This study delves into the photoluminescent characteristics of solid-state hybrid carbon dots/LAPONITE® (CDLP). These hybrid materials were synthesized using the hydrothermal method with a precise pH control set at 8.5. The LAPONITE® structure remains intact without structural collapse, and we detected the possible deposition of carbon dots (CDs) aggregates on the clay mineral's edges. The use of different concentrations of citric acid (10-, 6-, 2- and 1-times weight/weight of LAPONITE® mass, maintaining the 1 : 1 molar ratio with ethylenediamine) during synthesis results in different CDs concentrations in CDLP-A (low precursors concentration) and CDLP-D (high concentration) with an amorphous structure and average size around 2.8-3.0 nm. The CDLP displayed visible photoluminescence emission in aqueous and powder, which the last underwent quenching according to lifetimes and quantum yield measurements. Low-temperature measurements revealed an enhancement of the non-radiative pathways induced by aggregation. Energy transfer modelling based on Förster-Dexter suggests an approximate mean distance of 9.5 nm between clusters of CDs.

Enhancement in absorption spectrum by ITO coated, down converting glass and increasing the SILAR cycles of PbS/CdS quantum dots sensitized ZnO nano with deposition of MoO3/Au/MoO3 (MAM) as a solid state solar cell

This research describes the first-of-its-kind quantum dots sensitized solar cell (DC/ITO/ZnO/PbS/CdS/MoO3/Au/MoO3) that is efficient and economical. A down-converting (DC) transparent glass was prepared. One side of DC glass was coated with indium tin oxide (ITO) by sputter-coating technique to make it conductive for electric current. Zinc oxide (ZnO) nanorods were produced by the several steps of hydrothermal process. The PbS/CdS quantum dots (QDs) were then grown on top of ZnO nanorods by using a process known as Successive Ionic Layer Adsorption and Reaction (SILAR). The final layer for the back contact was deposited as a trilayer of (MoO3/Au/MoO3).Spin coating was employed in the process of depositing MoO3 layers, while thermal evaporation was used in the process of depositing the intermediate layer of gold (Au). For the deposition of (CdS/PbS) quantum dots with different number of SILAR cycles (10, 15 and 20) were employed. Afterwards MoO3/Au/MoO3 trilayer was deposited on the quantum dots (CdS/PbS) attached with the nanorods ZnO for the complete fabrication of three devices. As compared to the other quantum dots sensitized solar cell (QDSSC), it can absorb light from both ends which produced the remarkable results. Surface morphology, elemental and structural analyses were employed by SEM, EDS and XRD methods. UV–Visible analysis was performed to identify the optical properties of the devices. Overall performances were calculated of the three different devices by their power conversion efficiencies. The highest efficiency among all three devices was 10% corresponding to the 15 SILAR cycles.

Facile Synthesis of Carbon Dot Deposited γ-FeOOH Nanosheet/Polypyrrole Composite: A Robust Photocatalyst for Degradation of Antibiotics under Sunlight Irradiation with Enhanced Antibacterial Activity

This work reports the fabrication of a nanocomposite using carbon dot-deposited γ-FeOOH/polypyrrole composite through a facile in situ growth of γ-FeOOH, polymerization of pyrrole, and deposition of carbon dots (CDs) in a single pot along with its application as a photocatalyst toward degradation of antibiotics under sunlight irradiation. Here, the expired pharmaceutical drugs (waste) were used as a source of the synthesis of CDs to realize a “waste-to-wealth” approach. A series of nanocomposites (PFL/CDs-x; x = 1, 2, 3, and 4) with different γ-FeOOH content have been synthesized, and their photocatalytic activity was studied. Among all composites, PFL/CDs-2 exhibited the highest degradation efficiency of 97% within 90 min. The optimized γ-FeOOH and CD content in PFL/CDs-2 enhanced light trapping, charge separation, surface area, and formation of distinct heterojunction, indicating it as a promising candidate in photocatalysis. The excellent photocatalytic activity of PFL/CDs-2 can be attributed to synergistic enhancement of the light harvesting due to slow photon effect of the γ-FeOOH nanosheet and the inhibited recombination rate of photoexcited charge carriers based on a Z-scheme photocatalytic mechanism. In addition, the antibacterial potential of the synthesized nanocomposite was studied against Bacillus pumilus (Gram-positive) and Escherichia coli (Gram-negative) bacteria. Moreover, the PFL/CDs-2 composite was found to be magnetically separable and recycled without a significant loss of photocatalytic efficiency after four cycles, indicating the high reusability and stability of the photocatalyst.

In-situ deposition of lead halide perovskite quantum dots in mesoporous YF3:Eu3+ matrices with multi-wavelength emission and remarkably enhanced stability

Lead halide perovskite quantum dots (CsPbX3 PQDs, X = Cl, Br and I) have aroused wide concerns due to their outstanding optoelectronic characteristics. However, the simultaneous promotion of both high luminescence performance and brilliant stability is still a major challenge for their practical applications. Herein, Eu3+ doped YF3 nanospheres with hollow mesoporous structure are used to construct reactors for in-situ depositing CsPbX3 QDs through hot injection method. The as-synthesized CsPbBr3+YF3:Eu3+ nanocomposites exhibit multi-wavelength emission consisting of blue from self-trapped excitation (STE) emission of YF3 host, green from CsPbBr3 excitonic peak and red from characteristic emission lines of Eu3+. Besides, CsPbX3+YF3:Eu3+ composites with different halide compositions have been prepared and show multicolor emission with a wide color gamut. It is interesting to note that the stability of CsPbBr3+YF3:Eu3+ nanocomposites is remarkably enhanced under humid air, UV irradiation, and high temperature conditions compared to pristine CsPbBr3 QDs. This study provides new insights to realize stable CsPbX3 QDs-based multifunctional materials with multi-wavelength emission by combining with rare earth ions doped mesoporous materials and CsPbX3 QDs.

Optimizing the size and amount of CdS quantum dots for efficiency enhancement in CdS/N719 co-sensitized solar cells

Co-sensitization of TiO 2 photoanodes in solar cells with Ruthenium dye and quantum dots offer better photovoltaic performance compared to the sensitization by the dye only. In the present study, TiO 2 nanostructured photoanode was co-sensitized with CdS quantum dots and N719 dye. CdS quantum dots were deposited using successive ionic layer adsorption and reaction (SILAR). A suitable thin ZnS interfacial layer has been introduced between two sensitizers to prevent the corrosion of CdS quantum dots by the iodide-based liquid electrolyte. In order to get the highest efficiency, the number of SILAR cycles for CdS quantum dot deposition has been optimized. A power conversion efficiency of 6.79% with short-circuit current density of 15.55 mA cm −2 and open circuit voltage of 764.5 mV have been obtained for the co-sensitized solar cell made with TiO 2 /CdS/ZnS/N719 co-sensitized photoanode under the illumination of 100 mW cm −2 with AM 1.5 spectral filter. Efficiency and short-circuit current density of the solar cell have been enhanced by 11.31% and 6.58% respectively due to the co-sensitization. The optimized co-sensitized solar cell shows a higher incident photon to current conversion efficiency and a reduced electron recombination compared to the solar cell with dye-sensitized photoanode. Higher recombination resistance and longer electron lifetime of the solar cell with CdS/ZnS/N719 co-sensitized TiO 2 photoanode have contributed to the increased short circuit current and open circuit voltage leading to the enhanced efficiency of 6.79% which is among the highest for a co-sensitized dye sensitized solar cell . • TiO 2 photoanode was co-sensitized with CdS quantum dots and N719 dye. • ZnS layer was introduced between CdS and N719 to prevent the corrosion of CdS. • Number of CdS SILAR cycles was optimized to get the highest solar cell efficiency. • Solar cell efficiency of 6.79% was obtained for TiO 2 /CdS/ZnS/N719 photoanode. • New photoanode showed a high recombination resistance and long electron lifetime. • 6.79% is among the highest efficiencies reported for co-sensitized solar cells.

Recent Development of Quantum Dot Deposition in Quantum Dot-Sensitized Solar Cells

Recent Development of Quantum Dot Deposition in Quantum Dot-Sensitized Solar Cells

In situ deposition of 0D CeO2 quantum dots on Fe2O3-containing solid waste NH3-SCR catalyst: Enhancing redox and NH3 adsorption ability

As NOx has been turning into a crucial environmental problem, NH3-SCR technology with relatively simple device, reliable operation and low secondary pollution, has become a widely used commercial and mature de-nitration technology. However, some weaknesses restricted the further application of commercialized V2O5-WO3/TiO2 NH3-SCR catalysts, while Fe2O3-based catalysts have received much attention due to their high thermal stability, passable N2 selectivity and low cost. In this study, Fe2O3-containing solid waste derived from Zn extraction process of electric arc furnace dust was exploited as the base material for catalyst preparing. Owing to the complementary and synergistic effect of CeO2 and Fe2O3, 0D CeO2 quantum dots (CeQDs) with fully-exposed active sites, large specific surface area, and rapid charge transfer have been introduced and deposited onto Fe2O3-containing solid waste nanorods. The in-situ deposition of CeQDs led to the admirable enhancement in NH3-SCR catalytic activity, N2 selectivity and SO2 tolerance of the extremely low-cost Fe2O3 catalyst. Comprehensive characterizations and DFT calculations describing the adsorption of O2 and NH3 were applied to analyze the catalyst structure and further investigate the detailed relationship between structural properties and activity as well as reaction mechanism. This work provides new insights for the high-value utilization of iron-containing solid waste and a practical reference for boosting the performance of NH3-SCR catalysts by introducing quantum dots.

Ultrasensitive detection of breast cancer cells with a lectin-based electrochemical sensor using N-doped graphene quantum dots as the sensing probe

In this study, an ultrasensitive electrochemical biosensor fabricated from the deposition of nitrogen-doped graphene quantum dots (NGQDs) and phytohemagglutinin-L (PHA-L) onto screen-printed electrodes (SE) was successfully developed for breast cancer cell (MCF-7) detection in human serum. NGQDs with particle sizes of 3–12 nm were fabricated via a microwave-assisted hydrothermal method using passion fruit juice as the green carbon source, and then were conjugated with PHA-L through the amide bond between the COOH group of NGQDs and the NH2 group of PHA-L. The dual-functionalized NGQDs can enhance the electrical conductivity of the electrochemical sensor and serve as the nanocargo for PHA-L, a highly specific receptor for effective anchoring of MCF-7, and subsequently result in the ultrasensitive and highly selective detection of MCF-7. The prepared SE= |NGQDs/PHA-L sensor exhibited a wide linear detection range from 5 to 106 cells mL−1 in phosphate-buffered saline (PBS) and 20–106 cells mL−1 in human serum with extremely low detection limits of 1 and 2 cells mL−1, respectively. Moreover, the superior selectivity over 6 different interferents and long-term stability after 80 d of storage in human serum make the NGQDs/PHA-L complex an excellent sensing probe that can electrochemically detect low concentrations of cancer cells for the early diagnosis and treatment of breast cancer and other malignant neoplasms.

Neural network-based model predictive control for thin-film chemical deposition of quantum dots using data from a multiscale simulation

Recently, thin-film deposition of quantum dot (QDs) to manufacture solar cells and displays have received significant attention due to the lucrative optoelectronic properties of these devices. Unfortunately, (a) the existing macroscopic thin-film deposition models in the literature do not consider the surface-level interactions; (b) the detailed surface-level models do not consider the entire thin-film deposition ensemble; and (c) multiscale modeling studies considering both the scales are not tailored for QD systems. Thus, to address this knowledge gap, in this work, a multiscale thin-film deposition model is developed. First, the droplet distribution and evaporation dynamics during the thin-film deposition of QDs are described using heat and mass balance equations. Second, a microscopic discrete-element method (DEM)-based particle aggregation model that describes the surface-level particle interactions is developed and combined with the macroscopic dynamics. Furthermore, a model predictive controller (MPC) is designed to regulate the film thickness and minimize the film roughness by manipulating key process variables. To design a feasible MPC, a computationally efficient artificial neural network (ANN) model of the thin-film deposition model is constructed, and it is incorporated within the MPC. The closed-loop simulation results showcase the capability of the MPC to achieve the required film thickness and minimize the roughness.

Facile synthesis of a novel 0D/2D CdS/Bi4TaO8Br heterojunction for enhanced photocatalytic tetracycline hydrochloride degradation under visible light

A novel visible light-responsive 0D/2D CdS/Bi4TaO8Br nanocomposite photocatalyst with enhanced activity was synthesized by thein situdeposition of CdS quantum dots (QDs) on the surface of 2D Bi4TaO8Br nanoplates.

Effect of as flux rate during growth interruption on the performances of InAs/InGaAsP/InP quantum dots and their lasers grown by metal-organic chemical vapor deposition

We report the effect of As flux rate (FR) during growth interruption (GI) after quantum dot (QD) deposition on the performances of InAs/InGaAsP/InP QDs and their lasers, grown by metal–organic chemical vapor deposition. The active region consists of seven layers of self-assembled InAs QDs separated by InGaAsP lattice-matched to InP. Room-temperature photoluminescence (PL) measurements show that both the PL peak intensity and emission wavelength of the active region increase with As FR. Temperature-dependent PLs reveal that the activation energies of the QDs from the ground state to higher energy level or barrier become greater with the increase of As FR, indicating less carrier thermal escape from the QDs to their barriers. These above observations can be attributed to the promoted migration and suppressed desorption of surface In atoms, leading to enlarged QDs with deepened energy levels and thus enhanced carrier quantum confinement effect. Moreover, a 6-μm-wide and 3-mm-long ridge-waveguide QD laser with the greatest As FR shows a lowest threshold current of 477 mA under pulse mode at room temperature, corresponding to a threshold current density of 379 A/cm2 per QD layer. Meanwhile, the laser exhibits the highest characteristic temperatures T0 and T1 of 331 K and 775 K, respectively, in the temperature range between 20 °C and 60 °C.

Effects of PbS quantum dots layer and different light scattering films on the photovoltaic performance of double passivated PbS, CdS and CdSe quantum dots sensitized solar cells

In this research, two novel multi-layer photoelectrodes were fabricated and applied in quantum dot sensitized solar cells (QDSCs). The double layer scaffolds were composed of a TiO2 nanocrystalline sub-layer covered with an over-grown TiO2 nanorods (NRs) or ex-synthesized TiO2 hollow spheres (HSs) film. The light sensitization was carried out by deposition of separated PbS, CdS and CdSe quantum dots (QDs) layers. Finally, two electron blocking/passivating films of ZnS and SiO2 were formed for better photovoltaic (PV) performance. The syntheses of TiO2 nanocrystals (NCs), HSs and NRs were performed and tuned through different hydrothermal methods. The depositions of the PbS, CdS and ZnS layers were carried out by conventional successive ionic layer adsorption and reaction (SILAR) process. The CdSe and SiO2 films were also formed using a modified, effective chemical bath deposition (CBD) and sol–gel techniques, respectively. The PbS sensitizing film was additionally utilized for higher PV efficiency and the number of deposition cycles(X) was altered for the purpose of optimization. For the cell with novel TiO2NCs/TiO2NRs/PbS(X)/CdS/CdSe/ZnS/SiO2, X = 0–3, photoanode, the highest efficiency was about 5.5% and achieved for X = 2. This power conversion efficiency (PCE) was enhanced about 28% compared to that of the PbS free photoelectrode. The other improved TiO2 NCs/TiO2HSs/PbS(X)/CdS/CdSe/ZnS/SiO2, X = 0–3, photoanode was also utilized with a light scattering HSs film. The maximum efficiency was achieved about 6.5% for the extra PbS(2) sensitizing layer. This PCE was increased about 20% compared to the PbS free photoelectrode and 51% compared to that of the QDSC with the PbS free, NRs included photoanode. The highest efficiency was attributed to the co-sensitization and optimized PbS sensitizing layer together with the effective light scattering and utilization of double passivating layers.

Surface modification by high-energy heavy-ion irradiation in various crystalline ZnO facets.

Self-assembled surface nanoscale structures on various ZnO facets are excellent templates for the deposition of semiconductor quantum dots and manipulation with surface optical transparency. In this work, we have modified the surface of c-, m- and a-plane ZnO single-crystals by high-energy W-ion irradiation with an energy of 27 MeV to observe the aspects of surface morphology on the optical properties. We kept ion fluences in the range from 5 × 109 cm-2 to 5 × 1011 cm-2 using the mode of single-ion implantation and the overlapping impact mode to see the effect of various regimes on surface modification. Rutherford backscattering spectroscopy in the channeling mode (RBS-C) and Raman spectroscopy have identified a slightly growing Zn-sublattice disorder in the irradiated samples with a more significant enhancement for the highest irradiation fluence. Simultaneously, the strong suppression of the main Raman modes and the propagation of the modes corresponding to polar Zn-O vibrations indicate disorder mainly in the O-sublattice in non-polar facets. The surface morphology, analysed by atomic force microscopy (AFM), shows significant changes after ion irradiation. The c- and a-plane ZnO exhibit the formation of small grains on the surface. The m-plane ZnO forms a sponge-like surface for lower fluences and grains for the highest fluence. The surface roughness itself increases with the irradiation fluence as shown by AFM measurement as well as spectroscopic ellipsometry (SE) analysis. The damage caused by high-energy irradiation leads to non-radiative processes and suppression of the near-band-edge peak as well as the deep-level emission peak in the photoluminescence spectra. Furthermore, the refraction index n and the extinction coefficient k of irradiated samples, determined by SE, have features corresponding to the particular exciton states blurred and are slightly lower in the optical bandgap region especially for the polar c-plane ZnO facet.

Voltage-assisted SILAR deposition of CdSe quantum dots to construct a high performance of ZnS/CdSe/ZnS quantum dot-sensitized solar cells

The charge recombination on the interfaces of TiO2/quantum dots (QDs)/electrolyte is a key factor limiting the efficiency of quantum dot-sensitized solar cells (QDSSCs). Construction of double-layer barrier structure of ZnS/QDs/ZnS is a vital strategy to suppress the interfacial charge recombination. However, a large lattice mismatch (12%) at CdSe/ZnS interfaces causes CdSe to grow slowly on TiO2/ZnS mesoporous film, weakening the interaction between QDs and mesoporous film, which reducing the efficiency of CdSe QDSSCs with double ZnS barrier layers. Applying a voltage of 2 V in successive ionic layer adsorption reaction (VASILAR) to create an electric field, which assists Cd2+ and SeSO32− ions rapidly diffuse into the TiO2/ZnS mesoporous film to react forming CdSe QDs at room temperature. Optimizing the number of CdSe QDs deposition layers and combine with ZnS double-layer barrier structure, a best PCE of 4.34% for ZnS/CdSe/ZnS QDSSCs is achieved. This study gives a fast and simple approach to inhibit interfacial charge recombination to construct high performance CdSe QDSSCs.

DNA biosensor based on surface modification of ITO by physical vapor deposition of gold and carbon quantum dots modified with neutral red as an electrochemical redox probe

Here, we report on an effective modified DNA biosensor. First, the surface of an indium tin oxide (ITO) is modified with gold via physical vapor deposition technique. Second, we also report on the synthesis of carbon dots, which are modified with neutral red as an electrochemical redox probe. The different steps of modifications are monitored with atomic force microscope, UV–Vis spectroscopy, fluorescence spectroscopy FT-IR spectroscopy, dynamic light scattering and as well as different electrochemical techniques. The biosensor is applied for determination of salmonella DNA sequence at ultra-low concentrations with linear range of 20–240 fM and 10 fM limit of detection. The ability of detection of the target of biosensor is evaluated in spiked samples.